In an ink jet type recording head, while piezoelectric materials and conductive layers are alternately stacked as a piezoelectric vibrating element, either such a piezoelectric vibrating element of a longitudinal vibration mode expanding along an axial direction thereof, or a displacement type piezoelectric vibrating element which is provided on a surface of an elastic plate and is displaced by deflection is employed. In this ink jet type recording head, a pressure producing chamber, a portion of which is constituted by an elastic plate and is communicated to a nozzle opening, is expanded/compressed by a piezoelectric vibrating element, so that ink is refilled into the pressure producing chamber and the ink of the pressure producing chamber is pressurized. As a result, ink droplets are jetted from the nozzle opening.
The piezoelectric vibrating element having the longitudinal vibration mode has high rigidity, and can be driven at high speeds. On the other hand, this piezoelectric vibrating element owns such a problem that since this piezoelectric vibrating element is required to be assembled to the elastic plate in a three-dimensional manner, complex manufacturing steps are required.
To the contrary, in the latter-mentioned ink jet type recording head with employment of the deflection displacement type piezoelectric vibrating element, either the green sheet made of the piezoelectric material can be attached, or can be directly formed on the surface of the elastic plate by way of the film forming method. As a result, the manufacturing steps thereof can be simplified. However, this recording head with using the deflection displacement type piezoelectric vibrating element would require a larger displacement area than that of the recording head with using the piezoelectric vibrating element operable in the longitudinal vibration mode. Accordingly, the volume of the pressure producing chamber is increased, and thus the ink amount of the ink droplets jetted from this recording head is also increased. This recording head owns such a difficulty. That is, it is practically difficult to form dots having very small sizes such as graphic printing operation.
To solve such a problem, it is conceivable to reduce the displacement of the deflection displacement type piezoelectric vibrating element, so that the ink amount of the jetted ink droplets maybe decreased. However, the jetting pressure is also reduced, so that the speed of the ink droplets is lowered. As a result, there are errors at the ink impinge positions on the recording medium. In particular, there is such a problem that the printing quality is apparently deteriorated in a printing operation such as graphic printing operation that precise dots are required to be formed.
The present invention has been made to solve these problems, and has an object to provide an ink jet type recording apparatus capable of forming dots suitable for a graphic printing operation by that an ink amount for constituting ink droplets is reduced as small as possible without lowering jetting speeds of the ink droplets by way of a recording head in which a piezoelectric vibrating element is employed as a drive source.